Which of the following objects has the same length as that of the given 5 m thread?

(a) 500 cm long scale

(b) 50 km long road


(c) 50 mm long plate


(d) 5000 dm long paper

Dear Student,
According to unit scale:
1 m = 100 cm 
1 m = 0.001 km 
1 m = 1000 mm
1 m = 0.1 deca meter
1 m = 10 deci meter
So, according to the unit scale
5 m long thread = 500 cm long scale (option a).
Regards